1. Field of The Invention
This invention generally relates to connectors having ESD (Electrostatic Discharge) protection means, particularly to a female centronic type connector having a specific type front edge of its metal shield incorporating a shorter distance, relative to the contacts therein, with respect to an outside electrostatic charge source.
2. The Prior Art
As known, when the ambient relative humidity drops to fifty percent or below, the human body accumulates a large electrical charge. As disclosed in U.S. Pat. No. 4,824,377 to De Burro, such electrostatic voltage can be in excess of 20,000 volts which is normally dissipated without harm for a human under a situation that the person will be unaware that the electrostatic voltage has been discharged. However, this electrostatic discharge can be potentially damaging to certain electronic components. A specific instance of concern is when the electrostatic voltage is discharged into an assemblage of electronic components. More specifically, when a pin connector is unmated, the electronic components which are connected to this unmated connector are susceptible of receiving, through the conductive pins of the unmated connector, an electrostatic discharge which can result from an electrostatically charged human or other sources of an electrostatic charge.
Accordingly, De Burro uses a separate electrostatic discharge wire which transverses a path encircling or between two rows of pin insertion holes to catch or direct the electrostatic discharge thereto, thus preventing damaging levels of an electrostatic discharge from reaching the pins of the connector when not mated.
It can be appreciated that this type of pin connector is directed to a D-Subminiature female connector as disclosed in De Burro which has a substantial mating surface allowing installation of the wire thereof. In contrast, as disclosed in U.S. Pat. Nos. 5,102,353 and 5,104,326, a centronic type receptacle connector is generally disposed on the backplane of a computer and mating with a plug connector which has a blade inserted into the central cavity of this centronic type receptacle connector and having the traces along the edge for electrically engaging the corresponding contacts within the receptacle connector. It can be seen that there is no possibility for a centronic type receptacle connector to have a wire positioned between two rows of the female contacts because it will be an obstacle to insertion of the blade of the plug connector into the cavity of the receptacle connector. It is also unexpected to have a wire additionally attached onto the front mating surface of the centronic type receptacle connector and encircling those female contact passageways for ESD protection because there is hardly a sufficient space for loading a wire thereunto and forming a recess in a miniature connector to hold such wire therein. It tends to increase manufacturing problems and weakens the strength of the molded connector structure, especially in a miniature style connector. Another problem results from a relatively high volt electrostatic charge which may still easily jump the space and invade the internal electrical circuit through the contact even though the distance from the electrostatic charge source to the internal contacts of the connector is longer than that to the wire.
Accordingly, this invention is directed toward a new type of centronic type receptacle connector which provides ESD protection means directly on the shield which encloses the insulative housing with no separate additional wire needed.